1. Technical Field
The present invention relates to an electronic component having electrical connecting portions such as solder bumps or electrodes (lands, for example) exemplified by a solder bump component of a BGA (Ball Grid Array) type semiconductor component package (referred to as a BGA component hereinafter) represented by a CSP (Chip Size Package) or an electronic component such as QFP in forming an electronic circuit and relates to the mounting method and apparatus thereof.
2. Description of Related Art
In recent years, personal computers, portable telephones, information communications devices, multimedia electronic equipment, and the like have been compacted and provided with improved functions. Further, the electronic components and printed boards constituting electronic circuits have been made to have higher densities and finer constructions due to higher frequencies, and the mounting of components having a plurality of pins go mainstream in conformity to high-density circuits of QFP (Quad Flat Package) and the like. However, on increasing the density, the lead pitch of the connecting portions has been reduced in stages, for example, from 0.5 mm through 0.3 mm to the extent of 0.2 mm, for which the mounting method and manufacturing method themselves have become hard to be achieved.
It is further demanded for electronic circuits to cope with the reduction in size, higher functions, and higher frequencies, and this leads to a great desire to effectively mount printed boards with electronic components having solder bumps such as BGA (Ball Grid Array) represented by bare ICs of narrower lead pitches and CSP (Chip Size Package) and the like.
FIG. 15 is a front view schematically showing the land patterns of a QFP component and BGA components having solder bumps on a printed board. FIG. 16A is a sectional view of the BGA component having these solder bumps and the printed board to be mounted with the BGA component, while FIG. 16B is a bottom view of the BGA component. In FIG. 15 and FIGS. 16A and 16B, reference numeral 1 denotes a printed board, 2 BGA component connecting lands, 2′ QFP connecting lands, 3 BGA component use board recognition marks, 3′ QFP use board recognition marks, 4 BGA component land patterns, 4′ a QFP land pattern, 5 a BGA component that serves as an electronic component, 6 a bump-shaped solder connecting portions (referred to as BG connecting portions hereinafter) that serves as portions to be electrically connected via solder bumps 7 to the circuit board electrodes, and 7 the solder bumps.
There is further known a component mounting apparatus as shown in the partially see-through perspective view of FIG. 17 as a principal implement of a mounting position determining method of the component mounting apparatus. In FIG. 17, reference numeral 10 denotes a component mounting apparatus, 11 an operating section, 12 a control section, 13 a mounting head, 14 a mounting table, 15 a conveyance rail, and 16 a component supplying section. The component mounting apparatus 10 shown in FIG. 17 is mounted with the sliding component supplying section 16 and an X-Y table that serves as the mounting table 14 for holding and positioning a printed board.
FIG. 18 is a partially see-through perspective view of another component mounting apparatus. In FIG. 18, reference numeral 10 denotes a component mounting apparatus, 11 an operating section for executing inputting and outputting for the execution of a mounting program of NC data or the like, 12 a control section for controlling the whole mounting process by recognition, calculation, and various instructions in mounting components, 13 a mounting head for holding the component to be mounted and mounting the component on the board, 13a a component inspecting section for inspecting the component held by the mounting head, 13b a board recognizing section for recognizing the position of the board conveyed to the board mounting table, 14 a mounting table for holding the board that is conveyed so as to be mounted with the component, 15 a conveyance rail for conveying the board with respect to the mounting table 14, 16 a component supplying section for supplying the component to be mounted, 16′ a parts tray that serves as an example of the component supplying section 16 in which components are arranged in a matrix form, 16a a parts cassette that serves as an example of the component supplying section 16 in which tape components are stored, 16b a bulk cassette that serves as an example of the component supplying section 16 in which components are stored, and 16c a parts tray storing section for storing the parts tray 16′. As shown in FIG. 18, there is known the mounting apparatus having the above construction, which operates to pick up an electronic component from the component supplying section 16 by the mounting head 13 and move the electronic component held by the mounting head 13 to the mounting table 14 while recognizing the posture and so on of the electronic component held by the mounting head 13, thereafter moving the electronic component by the mounting head 13 to the mounting position on the board 1 held on the mounting table 14 and subsequently lowering the mounting head 13 to execute the mounting of the electronic component in the mounting position of the board 18. It is to be noted that the BGA components are generally stored in the parts tray 16′ or the parts cassette 16a. The components can be mounted in and supplied from the tape-shaped parts cassette 16a, the bulk cassette 16b for components stored in a scattered form, the component supply section 16′ that concurrently serves as a plate-shaped parts tray, and the like, which serve as a removable component set for continuously supplying the components. Further, the printed board 1 is conveyed onto the mounting table 14 for mounting the components, by the conveyance rails 15, and subjected to a specified mounting process, and thereafter the printed board 1 is conveyed to the outside by the conveyance rails 15.
Further, FIG. 19 shows a sectional view showing the mounting of a BGA component by the component mounting apparatus shown in FIG. 18. Solder paste 7′ is provided on the connection lands 2 of the printed board 1 shown in FIG. 16A, and the BGA component 5 supplied from the component supplying section 16 is held by the mounting head 13 and moved to a specified position of the printed board 1. Thereafter, as shown in FIG. 19, the BGA component 5 held by the mounting head 13 is depressed in the direction of the arrow D so as to connect the solder bumps 7 of the BG connecting portions 6 to the connection lands 2 of the printed board 1 via the solder paste 7′ provided on the lands 2.
The operation of the prior art electronic component mounting apparatus will be described with reference to FIG. 16. This component mounting apparatus 10 is to mount an electronic component (BGA component 5) on the printed board 1. On the component supplying section 16 or 16′ is provided a cassette or a tray conforming to the type of the electronic component necessary for actual mounting by the component mounting apparatus 10. Each cassette or tray supplies a component that is needed every moment.
The component necessary for the mounting is taken out by the mounting head 13, and the electronic component is subjected to component recognition executed by the component inspecting section 13a and to quality check (good-or-bad decision) and retention posture check of the component by comparing the result of recognition with the shape preparatorily stored in the control section. On the basis of the result of this check, posture correction data of the component is stored in the control section in a correction process as needed, and then, the target mounting land position on the printed board 1 is recognized by the board recognizing section 13b. Thereafter, the electronic component held by the mounting head is positioned in the recognized mounting land position, and the electronic component is mounted on the board with a certain accuracy after executing posture correction based on the posture correction data and board position dislocation data previously stored in the control station.
In mounting the BGA component 5 having the solder bumps 7, which is an electronic component as shown in FIGS. 16A and 16B, between the connection lands 2 on the printed board 1 and the BG connecting portions 6 of the connecting surface of the BGA component 5 cannot generally be checked for the confirmation of the component being mounted within a proper range since it is hidden behind the BGA component 5 in appearance after the component is mounted.
Therefore, according to the prior art mounting method or the mounting apparatus, as an example of the electronic component position detecting method for securing the mounting position and the soldering quality in mounting the BG connecting portions 6 on the board, the mounting is executed by detecting the position of the component based on the contour of the whole component through image recognition as disclosed in the Japanese Laid-Open Patent Publication No. 6-288732 or based on the state of the partial or total arrangement of the BG connecting portions 6 and the connecting surface.
However, according to the mounting method and apparatus of the component having solder bumps constructed as above, the actual positions of the BG connecting portions become uncertain in the case of only the contour, or much time is required in executing the positional detection of the BG connecting portions one by one. As a result, the time of recognition required for the positional detection of the BG connecting portions themselves influences the time of the mounting cycle. Therefore, the positional detection has been partially executed instead of executing the positional detection of all the BG connecting portions, meaning that the processing has been executed without correct positional detection.
With regard to the arrangement pattern of the BG connecting portions in the connecting surface of the BGA component, a variety of patterns based on the matrix pattern as shown in FIG. 20A including variations such as a pattern in which the BG connecting portions are partially not existing, as shown in FIG. 20B through FIG. 20J, must be recognized. Since such a variety of patterns are requested to be recognized, the partial positional detection of the BG connecting portions solely becomes incorrect. The state of partial or whole arrangement of the BG connecting portions is subjected to a recognition process such that the contour is set in the position detecting process since no definite reference point for executing image processing exists.
Furthermore, in order to recognize and check the correct position and pattern, a greater processing storage capacity, a complicated algorithm, and so on for the check are needed to consume much processing time, and the time required for the processing exerts a great influence on the time of the mounting cycle. Particularly in the case of the BGA components having irregular patterns as shown in FIGS. 20H through 20J, more complicated processing and memory resources are required, and this has led to the problem that the positional detection and the arrangement pattern recognition are practically difficult.
The present invention solves the aforementioned prior art problems and has the object of providing an electronic component as well as mounting method and apparatus of the component that are able to recognize the state of arrangement of the whole electrical connecting portions easily and correctly at high speed in mounting the electronic components such as: a BGA component represented by, for example, CSP having solder bumps for forming an electronic circuit; or a QFP component having no solder bump for forming an electronic circuit and satisfies a reliable component mounting quality of a high productivity.